+ * This module, both source code and documentation, is in the + * Public Domain, and comes with NO WARRANTY. + *+ * + *
If a SAX application requires the customized handling which this + * interface defines for external entities, it must ensure that it uses + * an XMLReader with the + * http://xml.org/sax/features/use-entity-resolver2 feature flag + * set to true (which is its default value when the feature is + * recognized). If that flag is unrecognized, or its value is false, + * or the resolver does not implement this interface, then only the + * {@link EntityResolver} method will be used. + *
+ * + *That supports three categories of application that modify entity + * resolution. Old Style applications won't know about this interface; + * they will provide an EntityResolver. + * Transitional Mode provide an EntityResolver2 and automatically + * get the benefit of its methods in any systems (parsers or other tools) + * supporting it, due to polymorphism. + * Both Old Style and Transitional Mode applications will + * work with any SAX2 parser. + * New style applications will fail to run except on SAX2 parsers + * that support this particular feature. + * They will insist that feature flag have a value of "true", and the + * EntityResolver2 implementation they provide might throw an exception + * if the original SAX 1.0 style entity resolution method is invoked. + *
+ * + * @see org.xml.sax.XMLReader#setEntityResolver + * + * @since SAX 2.0 (extensions 1.1 alpha) + * @author David Brownell + * @version TBD + */ +public interface EntityResolver2 extends EntityResolver +{ + /** + * Allows applications to provide an external subset for documents + * that don't explicitly define one. Documents with DOCTYPE declarations + * that omit an external subset can thus augment the declarations + * available for validation, entity processing, and attribute processing + * (normalization, defaulting, and reporting types including ID). + * This augmentation is reported + * through the {@link LexicalHandler#startDTD startDTD()} method as if + * the document text had originally included the external subset; + * this callback is made before any internal subset data or errors + * are reported. + * + *This method can also be used with documents that have no DOCTYPE + * declaration. When the root element is encountered, + * but no DOCTYPE declaration has been seen, this method is + * invoked. If it returns a value for the external subset, that root + * element is declared to be the root element, giving the effect of + * splicing a DOCTYPE declaration at the end the prolog of a document + * that could not otherwise be valid. The sequence of parser callbacks + * in that case logically resembles this:
+ * + *
+ * ... comments and PIs from the prolog (as usual)
+ * startDTD ("rootName", source.getPublicId (), source.getSystemId ());
+ * startEntity ("[dtd]");
+ * ... declarations, comments, and PIs from the external subset
+ * endEntity ("[dtd]");
+ * endDTD ();
+ * ... then the rest of the document (as usual)
+ * startElement (..., "rootName", ...);
+ *
+ *
+ * Note that the InputSource gets no further resolution. + * Implementations of this method may wish to invoke + * {@link #resolveEntity resolveEntity()} to gain benefits such as use + * of local caches of DTD entities. Also, this method will never be + * used by a (non-validating) processor that is not including external + * parameter entities.
+ * + *Uses for this method include facilitating data validation when + * interoperating with XML processors that would always require + * undesirable network accesses for external entities, or which for + * other reasons adopt a "no DTDs" policy. + * Non-validation motives include forcing documents to include DTDs so + * that attributes are handled consistently. + * For example, an XPath processor needs to know which attibutes have + * type "ID" before it can process a widely used type of reference.
+ * + *Warning: Returning an external subset modifies + * the input document. By providing definitions for general entities, + * it can make a malformed document appear to be well formed. + *
+ * + * @param name Identifies the document root element. This name comes + * from a DOCTYPE declaration (where available) or from the actual + * root element. + * @param baseURI The document's base URI, serving as an additional + * hint for selecting the external subset. This is always an absolute + * URI, unless it is null because the XMLReader was given an InputSource + * without one. + * + * @return An InputSource object describing the new external subset + * to be used by the parser, or null to indicate that no external + * subset is provided. + * + * @exception SAXException Any SAX exception, possibly wrapping + * another exception. + * @exception IOException Probably indicating a failure to create + * a new InputStream or Reader, or an illegal URL. + */ + public InputSource getExternalSubset (String name, String baseURI) + throws SAXException, IOException; + + /** + * Allows applications to map references to external entities into input + * sources, or tell the parser it should use conventional URI resolution. + * This method is only called for external entities which have been + * properly declared. + * This method provides more flexibility than the {@link EntityResolver} + * interface, supporting implementations of more complex catalogue + * schemes such as the one defined by the OASIS XML Catalogs specification. + * + *Parsers configured to use this resolver method will call it + * to determine the input source to use for any external entity + * being included because of a reference in the XML text. + * That excludes the document entity, and any external entity returned + * by {@link #getExternalSubset getExternalSubset()}. + * When a (non-validating) processor is configured not to include + * a class of entities (parameter or general) through use of feature + * flags, this method is not invoked for such entities.
+ * + *Note that the entity naming scheme used here is the same one + * used in the {@link LexicalHandler}, or in the {@link + org.xml.sax.ContentHandler#skippedEntity + ContentHandler.skippedEntity()} + * method.
+ * + * @param name Identifies the external entity being resolved. + * Either "[dtd]" for the external subset, or a name starting + * with "%" to indicate a parameter entity, or else the name of + * a general entity. This is never null when invoked by a SAX2 + * parser. + * @param publicId The public identifier of the external entity being + * referenced (normalized as required by the XML specification), or + * null if none was supplied. + * @param baseURI The URI with respect to which relative systemIDs + * are interpreted. This is always an absolute URI, unless it is + * null (likely because the XMLReader was given an InputSource without + * one). This URI is defined by the XML specification to be the one + * associated with the "<" starting the relevant declaration. + * @param systemId The system identifier of the external entity + * being referenced; either a relative or absolute URI. + * This is never null when invoked by a SAX2 parser; only declared + * entities, and any external subset, are resolved by such parsers. + * + * @return An InputSource object describing the new input source to + * be used by the parser. Returning null directs the parser to + * resolve the system ID against the base URI and open a connection + * to resulting URI. + * + * @exception SAXException Any SAX exception, possibly wrapping + * another exception. + * @exception IOException Probably indicating a failure to create + * a new InputStream or Reader, or an illegal URL. + */ + public InputSource resolveEntity ( + String name, + String publicId, + String baseURI, + String systemId + ) throws SAXException, IOException; +}